


Why Fight Nature?

by Kateri



Category: Merlin (TV)
Genre: Alpha Arthur, Alpha/Beta/Omega Dynamics, Dubious Consent, Half-Sibling Incest, Incest, Knotting, M/M, Mating Cycles/In Heat, Omega Merlin, Omega Verse, Smut, Underage Sex
Language: English
Status: In-Progress
Published: 2015-08-24
Updated: 2015-12-13
Packaged: 2018-04-16 23:39:11
Rating: Explicit
Warnings: Underage
Chapters: 5
Words: 6,801
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4644360
Author URL: https://archiveofourown.org/users/Kateri/pseuds/Kateri
Summary: <blockquote class="userstuff">
              <p>Arthur is an Alpha but is not allowed near the Omegas that live on the estate, his father's lovers and his half siblings. As he prepares to leave for University though all he can think about is whether he will have a chance to finally knot an omega while there. An unexpected gift though is dropped in his lap and why should Arthur fight nature when they both need this?</p>
            </blockquote>





	1. To Knot Obey Instinct Would Be Folly

**Author's Note:**

> Dub-Con due to Heat and underage sex.
> 
> A/B/O verse where an Alpha, Beta, or Omega can only be born if one of their parents is. A/B only produce alphas and betas, B/O only produce betas and omegas and so on. Mating instincts/desires and social morals are very different.
> 
> Written for the prompt "Anything involving a/o and incest. Maybe it was believed blood ties over rode mating instinct, maybe it was deemed impossible for parents to give birth to both an alpha and omega child, or maybe everyone tried to keep Arthur and Merlin apart once they came of age. "

Back in the days of kings and nobles ruling over the land Omegas were considered to be the property of kings. Only the royal family and those they gave permission too could wed and knot them. Later as humanity understood genetics and inheritance better it slowly became more acceptable for the common man to marry Omegas. An Alpha and Omega pairing still tended to remain in the sphere of the wealthy and influential though due to the need to be able to maintain separate households for their Alpha and Omega children. As society changed, morals concerning Alpha and Omegas did as well and most ignored their biological needs and settled down with a Beta. 

Arthur lay bored on the couch in his father’s manor house cursing his wealthy and noble ancestors in general and his randy Omega loving father in general. Most Alphas never knotted an Omega and if they did they satisfied themselves with a few rolls in the metaphorical hay with an Omega on contraceptives before settling down with a nice Beta spouse and popping out 2.5 kids to live with a dog and picket fence. Not Uther Pendragon though. Such a mundane existence was beneath him and there was no way that he would give up Omegas or risk have a Beta heir. No Uther Pendragon married a young socialite Omega, knotted and breed the Omega wives of friends, took on young Omegas as lovers who lived in multiple households on his family estate and even impregnated the Omega nanny he had hired to care for his young children and older Omega after his wife’s passing. 

So Arthur Pendragon, the only legitimate Alpha heir of his father, was consigned to living with his father, half-brother Kay and the half-sister of his half-sister Morgause in the manor house while two households full of Omegas, most of them half-siblings of Arthur, lived on the estate but were off limits. Sometimes Arthur wished he was like most of the other Alpha students at his school, with beta and alpha siblings, whose closest encounter with an Omega was standing outside the local Omega boarding school and sneakily talking to students through the wrought iron fence. Instead Arthur had to contend with sitting across the dinner table from Omegas twice a month during family dinners and smelling the scent of an Omega in heat wafting across the property from the Omega house that he was not allowed to enter. 

Ever since he had popped his knot and made it obvious that he was an Alpha Arthur had ached to burry it in an Omega. Not satisfied with fucking beta girls or watching fake Omega porn like his friends Arthur would sneak out when one of Uther’s Omegas were in heat and get as close to the building as possible and listen to their screams as they begged for Uther’s knot. 

Uther ran a tight household with all of his children, plus Morgause, living in the Nursery House at first, cared for by Hunith Emrys and occasionally the mothers of the children when they were still young. The children were only allowed to stay there though until the Alphas were identified at the beginning of puberty when their knot began to grow and they were moved into the manor house with Uther. The Omegas remained until their first heat positively identified them and then moved into the Omega house, the domain of Nynieve and Nimueh currently but many Omegas had resided there over the years and not all had given Uther children. 

Arthur had presented at thirteen and moved into the Manor house, roughly the same age that Morgause and Kay had. Most of his Omega siblings had gone into their first heat at around fifteen, sometimes fourteen. None had left home yet so all five, Morgana, Elaine, Madoc, Ninianne, and Freya, lived there still. Currently Hunith only had three children in residence, young Nynieve’s son Guivret, Vivianne’s youngest Mordred and Hunith’s son Merlin.

Arthur only occasionally visited the Nursery House’s large porch but was never allowed entrance and since Merlin and Mordred were both thirteen they would most likely be moving soon. Arthur sincerely hoped that Mordred did not present as an Alpha, he found him more than a bit creepy, but apparently much beloved by his older sisters. Merlin on the other hand was an okay kid, easily embarrassed at times but very plucky and willing to stand up against those bigger and older than him for what he thought was right. It was all of the fights in and after school that had Uther preparing another room in the Manor, sure that his only child by Hunith would turn out an Alpha. Considering how willing some of his Omega siblings were to yell at their father Arthur wasn’t so sure that Merlin’s willingness to argue was so much an Alpha trait as such, more a Pendragon trait but would agree that Merlin appeared to be maturing at an Alpha rate. 

Rubbing his dick lightly through his jeans Arthur tried not to dwell on the forbidden Omegas living only a few hundred yards from him and instead on the possibilities that would be open to him in just a few days when he moved into his place for University. A coed institution, Avalon enrolled all sexes and genders. Most Omegas still lived in group houses and tool suppressors and contraceptives which meant that they would not got into Heat or be able to conceive but could be seduced or caught breaking curfew at a late night party or club. Arthur could almost picture it, a nubile young Omega, male possibly, pressed against a wall in a dark corner, begging him to fill him up. As he pressed harder on his trapped cock Arthur could practically smell the scent of Omega in heat. 

Taking a deep breath through his nose Arthur suddenly bolted off the couch as he heard a sob and realized that he actually was smelling an Omega in heat. Panting and red faced Merlin stood in the doorway, his glazed eyes lazily sliding past Arthur before darting back to the blond and clearing slightly.

“Arthur,” Merlin gasped with a sob in his tone, “Something’s wrong, it hurts and won’t stop.”

Arthur found himself unable to reply, struck silent by the sight in front of him. His thirteen year old brother stood in the door way smelling of Heat and dressed in a bathrobe, t-shirt, and boxers, said boxers soaked from where fluid dripped down his legs still plump with what before today Arthur had assumed was baby fat and his cock peeping out of the slit, an angry red color and leaking from the tip. 

“No matter how much I wank it won’t stop, make it stop Arthur,” Merlin sobbed, his hand sliding into his boxers and tugging at his cock, causing the smell of Omega to flood the room. 

“Don’t worry Baby Bird, I’ll help you,” Arthur found himself saying, his groin tightening in anticipation. “Where’s your mom and Mordred?”

“Mordred’s mum picked him up for a week, and mum is in Scotland and won’t be back for days because she is at the hospital with Uncle Gaius,” Merlin answered, his bottom lip quivering “I’m all alone at the house because Nynieve took ‘Ret to stay with her and don’t know what to do Arthur.”

Arthur licked his lips, weighing the odds. He could walk Merlin over to the Omega house and let someone there handle Merlin but if Hunith was at the hospital with her Uncle than she wouldn’t be able to check on Merlin herself for days probably, a call that he was staying in the manor would take care of her. Morgause and Kay had left yesterday for school, his father was on a business trip to Tokyo, and none of the servants were scheduled to stop by before he was supposed to leave for Avalon. None of the residents of the Omega House ever came to the Manor unless his father ordered it, so there was no one that could stumble upon them and stop him. 

“Don’t worry Baby Bird, I know just what to do.” Arthur answered taking a step toward Merlin in anticipation. 

Uther had children by five different Omegas, it was his fault, Arthur thought as he reached out to take Merlin’s hand and lead him up the stairs. It was cruel to father so many sweet little omegas and deny them Alpha knots when they needed them, just as it was wrong to deny Arthur the chance knot an omega. Besides, his little Baby Bird was his favorite sibling and he couldn’t let him suffer.

696969696969

Arthur quickly led Merlin up the stairs to him room, a place that Merlin had never been before and as an Omega should never be. Arthur refused not to take advantage of what was being handed to him practically gift wrapped though. Even today most Alphas never got to knot an Omega, much less one in Heat. The Omegas willing to go through their Heats instead of chemically suppressing them until marriage tended to be snapped up by people like his father as live in mistresses. Arthur had no intention of waiting until marriage to experience what fucking and knotting an Omega was like. 

Locking the door behind them despite the empty house Arthur paused to take in Merlin. The Omega was flushed and was rubbing his erection through his boxers. In recent months Arthur had thought Merlin had started bulking up some, leaving his slenderness behind with the exception of his legs. Merlin’s thighs had always retained a hint of the chunky toddler he had been. How true this was Arthur didn’t know as Merlin had not joined him in the pool all summer and had taken to wearing several layers of shirts. Now he wanted nothing more than to see the changes that had obviously been happening that Merlin seemed to have been hiding.

Striding across the room to his bed Arthur took a seat before calling Merlin over.

“Come on over here Little Bird so I can help you,”

“Not little anymore,” Merlin mumbled as he stumbled over until he stood glassy eyed in front of Arthur.

“Let’s get all these uncomfortable and hot clothes off so I can take good care of you Merlin,” Arthur said “and you will always be MY Little Bird, my little hawk. After all I’m the one that chose your name.”

Arthur’s hands shook as he removed an uncomplaining Merlin’s cloths. First the bathrobe slid off of his shoulders and then he peeled the t-shirt up over Merlin’s head and finally slid the boxers down over Merlin’s hips revealing the sweet young omega’s body. 

Though Merlin was young and this was his first Heat Arthur was surprised at how much the revealed Omega’s body had changed from when he had run around last summer in swim trunks. Merlin’s hips had already thickened and spread, showing that while he might only be thirteen his body was mature and ready to carry young. His waist was slender, but not too slender and led to the most perfect chest. It was a mixture of masculine and feminine that had Arthur wanting to take the small breasts into his mouth and suck them until Merlin screamed in pain. God they were gorgeous with stiff little rosy nipples that begged to be bitten. His shoulders were broad, his legs long, and his cheekbones sharp. 

Now that he was naked Arthur couldn’t believe that no one had realized that Merlin had developed into an Omega, especially one that appeared to have matured so far before his first Heat. A male Omega’s body did not normally start to develop any of the characteristics necessary for carrying a child until their first Heat flooded their body with hormones triggering the changes that had already happened to Merlin. As much as he wanted to look though Arthur’s desire to fuck his knot into the wet heat of the little Omega was greater and he would have plenty of time later to explore. 

“Alright Merlin are you ready for me to help you?” Arthur asked, barely restraining himself from just tossing him onto the bed and instead settled a hand on Merlin’s hip, aching to grab what he was sure was a luscious ass.

“You can make it stop right Arthur?” Merlin asked, his hands fluttering about as if unsure what to do with them as he stood naked in front of his brother.

“Yes I can, but you need to get up on the bed, face down so that I can give you what you need.” Arthur said.

Quickly Merlin complied, lying face down on Arthur’s bed, his legs unconsciously falling open and exposing his leaking hole to Arthur.

Quickly stripping out of his own clothes Arthur climbed onto the bed behind Merlin and gripped one of his ankles. He smiled as he felt how hot the trembling limb was.

“Don’t worry Merlin, I know just what you need.” Arthur said as he ran his hand up and down Merlin’s leg. “I know how to get rid of the emptiness and hurt.”

As his hand reached Merlin’s thighs his rear made a tiny thrust backward and a gush of slick made its way out of his ready hole.

“Are you hot Merlin?” Arthur asked feeling excited and commanding “Are you burning up inside?”

“Hurts Arthur, too hot and empty,” Merlin whimpered “Make it stop, fix it please.”

“There’s only one way to help you Little Bird, you need something to fill you up. You need something stuffed up here.” Arthur said as he slipped a finger into the wet loose hole and groaned as Merlin shoved his ass back and whimpered.

“But not just anything will help Merlin, do you know why?” Arthur asked as he worked his finger in and out of Merlin’s leaking Omega boy cunt. “Only an Alpha knot will make it better because you’re an Omega. Your cunt knew what you needed, that’s why you came to me, so I could stick my knot in you and make us both feel good.”

He couldn’t wait any longer and couldn’t be bothered to take the time to make sure that Merlin could take him, he had to get inside of his Heat crazed Omega brother. He had to fuck him now.

“You like that Merlin? Does that feel good?” Arthur ground out as he grasped Merlin’s legs behind the knees and pulled them and to the side of the prone body, forcing Merlin’s legs to splay out to the side of his now slightly raised ass.

“I’m going to fill you up and drown that fire in you Little Bird, I’m going to fill you up.” Arthur said, panting with lust as he gave his now fully engorged cock a few pulls and enjoyed the whimpers and breathy moans of the virgin Omega whose cherry he was about to pop. 

‘God!’ Arthur thought, ‘he was about to fuck and knot his favorite brother who was in fucking heat and he was going to love every minute of it.’

Arthur quickly guided his cock in-between Merlin’s cheeks and teased his hole twice before he pushed forward. It took a moment but as soon as the head of his cock disappeared into the body of his brother Arthur grabbed one of Merlin’s shoulders and used his grip to pull the body back onto his cock as he thrust forward. The pleasure as his cock was engulfed by the fiery tightness of the quivering omega was like nothing Arthur had felt before. With no thought he pulled back and thrust back in again and again, changing his angle and grip, looking for the perfect position to pound into the quivering and moan mess beneath him.

Arthur couldn’t believe that he had had Omegas living so close to him all this time and he had never fucked one. The tight heat clenching around his cock was better than any beta pussy he had fucked and the heat scent pouring off of Merlin was driving him wild. The moans and sobs coming from his little brother were better than any dirty talk from any of the girls he had fucked. He felt like a god as he fucked deeper and deeper into the small body, unable to believe that it could take almost his entire cock again and again. The heat and tightness gripping him was unbelievable and he quickly became lost in the feeling of sinking into Merlin. 

“Oh god you’re perfect,” Arthur panted “Just so fucking perfect, you were made for fucking!” 

“Arthur!!” Merlin wailed, his head turned to the side trying to look at his brother who was busy fucking him.

“Yes! Arthur, your Alpha,” Arthur grunted, “God look at how well you take my cock. I’ve stuffed it up so far in you and I’m gonna fuck that burning right out of you. I’m gonna shove my knot in so deep that whenever I’m not inside you, you are going to feel empty and loose!”

“Yes Alpha! Yes!” Merlin cried as his body shook as he came.

It was not enough though to calm the raging lust and need of his Heat and he cried out for more, for something that he didn’t know but craved deeply.

After the second time Merlin clenched around him as the Omega came Arthur lost all sense of anything but the need to go deeper, so deep that no one else would ever reach it, that Merlin would never forget how completely Arthur owned him. No matter what he could not sink as deep as his body craved until with one harsh thrust Arthur lost his balance and ended up held off of Merlin only by his elbows braced to either side of the sobbing Omega. Arthur spread his legs wide and covered Merlin’s body entirely. Practically plastered to Merlin Arthur was able to use the new position to at last slide the last inches of his cock into his brother’s tight ass.

The new depth that Arthur reached was too much though. With only a few thrusts Arthur found his knot swelling, locking him deep within Merlin. Between Merlin’s cries at the growing size of the giant knot buried in him and the pressure Arthur felt gripping his knot as he ground into the body beneath him he was sure that at any moment his prick would tear the small omega apart. Instead with a suddenness that had both of them gasping and trembling and falling off a cliff into an ocean of pleasure Arthur came.

Arthur’s swollen and Rut enlarged bollocks began to empty as he cummed deep inside Merlin, bathing his insides with cum. The sea of Alpha cum trapped by Arthur’s knot momentarily calmed the fire that had been raging inside Merlin allowing him to go limp beneath Arthur’s bulk in relief and pleasure. As he continued to spend deep inside Merlin Arthur was sure it would never stop, that he would continue to cum until Merlin’s belly grew distended and burst from Arthur’s spunk.


	2. Knot Letting Go

**Summary for the Chapter:**

> Still tied to his brother Arthur is already ready to fuck him again.

Arthur was careful to not rest all his weight on the smaller body he was currently tied to, his knot still swollen and lodged deep inside the sleepy Omega. Even with how hurried it was that was the best sex he had ever had and if that was what it was like with an Omega he couldn’t understand why any Alpha would want to go back to betas. Being able to fit his whole knot inside that raging heat alone made it better than anything he had felt before. 

Slowly Arthur rolled them to their sides and curled himself around Merlin and just enjoyed the feeling of his cock tied deep inside the Omega. Merlin’s body was still clamped down and even if his knot went down Arthur wasn’t sure he would be able to pull out. In some of the Heat Porn Arthur had watched the Alphas had gotten hard again and fucked the Omegas without even pulling out but some of his friends had claimed it was just porn and not real. The unrelenting clasp of Merlin’s body was leading Arthur to think that it was entirely possible that he would fuck Merlin again before his knot was released. 

Curious Arthur began to move his hips slightly, feeling his knot catch and pull on Merlin caused delightful sensations. After several minutes though Arthur grew tired of this and began to grind into the limp body. This felt even better and soon Arthur was clutching at Merlin’s hips to pull him closer as he ground his groin into his brother in a circular motion. About the time that Merlin began to emit small sleepy moans Arthur was once again erect and was overcome by the desire to rut. Rolling the pair of them over so Merlin was belly down on the bed with Arthur covering him and his hips thrusting against Merlin causing his knot to rub continuously against Merlin’s prostate. 

Arthur didn’t know how long he thrust his trapped cock deeper into Merlin before he realized that his brother was awake and sobbing and clawing at the bed. Delighted that he had caused this Arthur found his body freezing up as he came and cummed deep inside Merlin again. After what felt like forever as spurts of cum still jetted out of his cock into Merlin Arthur became aware of Merlin’s hips trying to move and quiet sobs.

“Please Alpha, make me come,” Merlin begged through tears of frustration “Please I need to,”

Considering he had already gotten two great orgasms out of Merlin and he had promised to take care of him Arthur reached under Merlin and wrapped his arms around him. Pulling his own knees under him Arthur then hoisted Merlin up as he sat up himself and settled back into a kneeling position with Merlin seated on his folded lets, still tied to him. Using one arm to secure Merlin to his chest Arthur grasped Merlin roughly with his free hand and began to stroke him roughly while he buried his face in his brother’s pale neck. Only slightly distracted by the need to keep his arm moving Arthur gave himself free rein to lick, bit and suck at the delicate neck beneath his lips. Just as Merlin shuddered and came the convulsions of his inner muscles wrung another small flood of spunk from Arthur and caused the Alpha to bite down on Merlin’s shoulder hard enough to bruise. 

Both of them satisfied for the moment Arthur carefully arranged them before closing his eyes for just a moment.


	3. Knot Ignoring His Desires

**Summary for the Chapter:**

> Merlin's Heat continues and Arthur is determined to have the Omega any way he wants while he can.

Arthur found himself jolted awake as his half hard cock was roughly stroked and tugged at. Seeing a flushed Merlin leaning over his groin, desperately trying to bring him to full mast had the day rushing back to Arthur. Unable to believe that he had fallen asleep, Arthur none the less felt invigorated and aroused, like he could fuck all day long now. Sitting up he grabbed Merlin by the shoulders and pushed the much smaller boy backwards. Ignoring his wines of outrage and the begging words Arthur climbed on top of him, straddling his chest. 

Licking his lips Arthur took his half hard cock and rubbed the tip of it against Merlin’s lips. When the boy opened them to let out a surprised gasp Arthur quickly fed it into his hot mouth. Watching his cock slip between those sinful lips had Arthur groaning and trying to force more of it into the moist cavern.

“Come on Merlin, just a little bit more,” Arthur said already hardening more. “Just suck at it, use your tongue.”

At the tentative suck and swipe of Merlin’s tongue Arthur groaned and thrust forward uncaring of whether or not Merlin could take him. As the Omega began to suck harder Arthur continued to make small thrusts until the depth he could reach wasn’t enough. Reaching down he grasped Merlin’s head and pulled it up, allowing him to thrust deeper and causing the pinned omega to start to squirm. 

A part of Arthur wondered if he was choking the boy but the feeling of those lips around his cock meant that he didn’t care, he needed more of his cock to slip past them. God the control he felt, forcing his cock between those lips, the sight of saliva dripping out the sides of Merlin’s mouth was almost as good as the sensation of his cock sliding in and out. Pulling out momentarily Arthur ignored Merlin’s gasps for air and ran his cock head over the boy’s face, painting it messily. Soon enough he forced it back between the omega’s reluctant lips and began facefucking him vigorously, holding Merlin’s head firmly between his hands. 

Arthur wasn’t sure how long he did this before he tired of the sensation and wanted more. As good as his mouth was Arthur wanted to get his knot lodged in Merlin’s sweet young omega ass again. Arthur had no idea how long it would be until he had another chance at barebacking someone, much less an omega and was going dump as much cum as he could inside Merlin during his heat while he could. 

Pulling out of Merlin’s slack mouth Arthur climbed off of the smaller boy and grabbed him to maneuver his Heat slicked body into the position he wanted. 

 

“Arthur, please!” Merlin begged as he was manhandled “I’m hot.”  
“Don’t you worry Little Bird,” Arthur said to the boy on his back as he pushed his knees up toward his sweat slicked chest, bending the Omega almost in two, “I’m gonna stick my cock back in your hot little hole and make the heat go away.”

“Arthur,” Merlin wined one hand grasping at Arthur while the other tried to grab his own erect little cock, the head purple with its need to come.

“Shhh….” Arthur replied reaching to stroke Merlin’s hair, “It felt real good when I did this before, remember? A big Alpha cock and knot in your little omega cunt is what you need to make the heat go away.” 

Not wanting to wait any longer Arthur grasped his throbbing cock and placed it at Merlin’s slick entrance and watched as it sank in. Pulling back slightly before pushing in even farther Arthur marveled at the stretch of the small hole around him, both welcoming the fleshy rod and trying to expel it. 

The deeper Arthur sank the louder and more insistent Merlin’s groans and begging became. Tiring of the slow pace Arthur shuffled closer to Merlin and pushed his knees to the side so that when he leaned over he could suck the boy’s tits. With his mouth occupied Arthur began moving his hips faster, his thrusts becoming deep and rapid, pounding into the bent body beneath his. Merlin’s groans became screams of pleasure as Arthur plunged deeper and deeper into his body until at last Arthur found his hips unconsciously grinding him into the ‘V’ of Merlin’s legs as his fully sheathed cock began to swell at his knot before he cummed deep inside the sobbing omega.

Hunched over the trembling body Arthur tried to thrust deeper as he spilled inside Merlin’s hot body, quenching the Heat fires momentarily. The pressure from Arthur’s knot on his prostate had the omega coming again and again, clenching around the flesh that impaled him and leaving his own spunk to decorate his quivering stomach. Despite his orgasm Arthur wasn’t satisfied and his trapped cock remained diamond hard in its fleshy prison. 

With a few movements Arthur worked his knees partially under Merlin’s back, leaving his bum and lower back to rest on Arthur’s thighs. Still bent over the small body Arthur reached under Merlin’s arms to grasp his shoulders and pull his body farther onto his cock as he continued to grind his hips into Merlin in a circular motion. The feeling of his knot shifting within the small Omega was fantastic and the constant small shudders that ran through his small frame felt delicious as they danced up and down his sheathed cock. 

Finding his face buried in Merlin’s neck Arthur began to suck and bite at the flesh beneath his lips, leaving mark after mark on the pale skin. By the time Arthur was done with him it was going to be obvious to anyone who looked at the boy that he had been thoroughly violated and had by an Alpha. Arthur was determined that by the end of his heat not one portion of Merlin’s body would remain unclaimed. 

Arthur didn’t know how long he maintained his motion but his second orgasm caught him by surprise as he once again shot wave after wave of cum deep inside Merlin, who let out a sigh of relief as his insides were soothed once again momentarily. This time he softened and his knot went down fairly quickly so that he was able to withdraw. The sight of his own spunk mixed with Merlin’s omega slick leaking from his brother’s wrecked hole caused Arthur’s prick to twitch but even an Alpha need some recovery time. Soon enough Merlin would be begging again for Arthur to fuck and in the mean time he could begin to explore the omega’s body.


	4. Knot Ever Giving Up What Is Mine

**Summary for the Chapter:**

> Arthur considers the future.

**Notes for the Chapter:**

> Okay, somehow Arthur got away from me and what I planned and turned out to be an even bigger perv than I intended. Just a warning that the incest tag is really deserved.

While Merlin lay in a satisfied daze Arthur took the time to run his hands all over the young body that lay next to his and explore it completely. He paid special attention to the fat little omega cock, temporarily limp and the still leaking hole all glistening and pink from taking Arthur’s cock. Arthur saved the best for last though, the two perfect mounds of flesh on Merlin’s chest. 

Arthur liked breasts just like any teenage boy but he had never been as drawn to a pair as much as he was Merlin’s. The small soft mounds were perfect in either his hand or his mouth and he used both. Taking the left one in his mouth Arthur began to suck on it, letting it go occasionally to let his mouth wander all over the pale flesh biting and licking it. Busy as he was he did not neglect Merlin’s other tit, making sure to kneed and squeeze it, even pinching at the rosy teat already pointed with arousal. 

Eventually Merlin’s tits could not distract Arthur from other needs and he left the sleeping Omega to take care of them. He returned quickly, refreshed and fed, bringing with him a tray of snacks and juices that he slowly began to feed to the groggy teen in his bed. The weight of Merlin leaning back against him as he gently slipped food and drink between the Omega’s swollen lips was arousing, as was the thought that the smaller boy would waste away if Arthur wasn’t here to make sure he ate and drank instead of fucking his whole Heat away. These actions made Arthur feel possessive and powerful and seeing that Merlin was erect and leaking again Arthur decided to put the food aside and possess his body once again.

Arthur rolled the still passive Omega onto his side and slid down the bed until he rested behind him. Fingering his entrance Arthur found it loose and still slick and leaking. Grasping Merlin’s right leg behind the knee Arthur pulled it up until it was bent and pressed against Merlin’s upper body, exposing more of his rear to the Alpha’s attention. Quickly lining his erection up Arthur pushed into the tight heat and began a slow fuck into the still sleepy but aroused omega.

Arthur grunted in exertion and pleasure as his cock continually sank into the tight grip of Merlin’s body. With the smaller boy on his side with his top leg pulled up to spread him out Arthur was able to comfortably thrust into the pliant body and still play with his swollen breasts. Arthur found it harder and harder to leave the small tits alone. They just felt so wonderful in his mouth or hands and he couldn’t help but imagine them swollen to a much larger size, filled with milk after delivering a babe or two. With Merlin’s still tiny size and mostly slender build they would look enormous and would be sure to bounce and jiggle with every movement of the omega.

Picturing how big Merlin’s tits could look in the future had Arthur spreading Merlin even wider as he began to thrust harder and more urgently, determined to knot the boy and tie them so he could fill him up with his spunk again. The closer Arthur got to his peak the more aroused he felt at the thought of once again spilling inside his brother. 

The bonds of family already gave Arthur claim over the other boy, and knotting him through his first heat meant that Arthur possessed the omega in a way no one else ever would. A tiny growing thought though had Arthur fucking deeply into Merlin though, nothing said possession quite like impregnating an omega. While the laws no longer gave an Alpha rights over Omegas they had bred and the Omegas were free to leave where would a pregnant teen go but with the Alpha that had tied them? No thirteen year old could support himself and his child without the help of his Alpha, and the more he was bred the closer the ties would be. 

Unable to contain his possessive feelings Arthur rolled the pair of them over so that Merlin now lay on his stomach and could rub his own cock against the bed beneath him. Fully awake now thanks to Arthur’s deep fucking the little omega was pleading for Arthur’s knot and sperm to once again help quell the fire he felt deep in his belly. It didn’t take long with the two of them working in concert to orgasm explosively and for Arthur to fall upon Merlin’s back as his knot tied him once again to the omega.

As Arthur spilled himself deep into the fertile body beneath him his earlier thoughts came back to him. The first heat was supposed to be light as normally an Omega’s body had not yet matured. Merlin though was sure to conceive with his tight little mature body unlike most teen omegas. Arthur could fill him up again and again and get him with child. He could take him with him and fuck him as his belly swelled, and as soon as the baby was born and weaned he could send it away to induce Merlin into Heat again. It was possible if Arthur fucked him enough he might even be able to induce a Heat without sending the child away. This thought warmed Arthur’s heart as he thought about it.

He would breed Merlin again and again and then all of them would live together in one great big home. And he would not lock up his Omega offspring, no Merlin would have all of them around him and when Arthur’s Omega children went into heat he would let the Alphas taste them and help their brothers and sisters through it just like Arthur helped Merlin. 

And if there were no alpha children Arthur might knot their soft bodies himself to relieve the fires in their bellies while Merlin watched and then take his mate again and again until both Omegas had a belly full of his seed. Arthur would have more children than his father but they would know they were loved instead of being hid away. 

“Do you know what’s happening to you Merlin?” Arthur asked the body pinned beneath his own and full of his seed “Do you know what you are?”

Merlin started to nod before violently shaking his head.

“Don’t lie to me Merlin, you knew what was happening and you hid it.” Arthur said sternly, desire to bend his stubborn little brother to his will running deep through his veins. 

“I can’t be an Omega,” Merlin sniffled “I can’t, I won’t be. I won’t live in the Omega House with those harpies. Father can’t keep me from seeing you!”

Arthur smiled as Merlin cried and reached back to grasp at the body that still pinned the omega’s to the bed, knotted and tied. Grinding into Merlin’s rear, making the omega very aware of the knot pressing against his prostate Arthur enjoyed Merlin’s gasps of arousal.

“But you are Merlin, you are an Omega. But you won’t be living with Father’s pathetic house of broodmares and he won’t be stopping us from seeing each other. I’m going to put a babe in you, I’m going to make you fat with my children. I’m going to take you with me and you’re going to be my mate. I’ll keep you in my bed and knot you every day. I’ll keep you so filled up with my spunk that you’ll always be pregnant with a big belly an huge tits. I might even get your mom to come stay with us after you have the first baby to take care of it because you’ll be too busy begging for my knot.”

Arthur grinned as Merlin whined and began to shudder beneath him as he orgasmed. Feeling his own cock twitch where it was still buried inside his mate Arthur began to fuck him again as much as his still engorged knot would allow. Arthur was determined to come at least one more time before his knot went down this time. Merlin had two more days of Heat most likely and Arthur was determined to enjoy it as much as possible.


	5. Warming Up

**Summary for the Chapter:**

> Yesterday Merlin's life began to spiral out of control

Merlin’s Side  
Merlin didn’t quite understand what was happening to his body but it scared him. He did his best to wear lots of shirts and baggy pants so no one could see his body. Late at night though he couldn’t help but run his hands over his growing hips and rub his sensitive nipples. What was happening to him was nothing like what they talked about in his health classes, about how your body might change as you grew older. The day after his mum left to go stay with her Uncle Gaius was the scariest day yet. 

When Merlin woke up that morning alone in the Nursery House he felt hot and achy. Afraid that he might have a fever he didn’t bother dressing and ate some breakfast and drank lots of water. The achy feeling never went away and when he went to bed that night wondering if Arthur would let him come stay with him up at the manor house tomorrow if he was still feeling sick. Merlin knew he wasn’t supposed to go there until he became an Alpha but Father was gone and Merlin loved spending time with Arthur. Soon he would be leaving for University and Merlin wouldn’t see the only sibling that actually cared for him for months. 

That night Merlin wanked five times, and was a bit worried about how sensitive his cock felt and how it kept springing back up. He knew that Alpha’s had a lot of sex but nothing else about his body was developing the way it should. The fears that lingered in the shadows of his mind tried to creep forward but Merlin steadfastly ignored them and instead thought of Arthur, his big strong Alpha brother and how he would go to him tomorrow. Arthur would make everything better. 

When Merlin woke in the morning it was to find that his fever felt much higher than before and he was laying in a giant wet spot. His boxers were encrusted with his cum and something else that Merlin ignored with all his might. As the morning passed the achy feeling from yesterday settled in his lower stomach and between his legs. Now all Merlin could think about was the empty feeling inside of him, almost like a hunger but no matter how much he ate nothing filled him. 

Late in the morning after tossing off yet again Merlin felt like crying. No matter how many times he came it didn’t help, his little cock stayed thick and red. Worse he was leaking out of his hole and it wouldn’t stop. Merlin didn’t know what to do, he wanted to come but it just wasn’t enough and the empty feeling was becoming all he could think about.

Finally it all became too much and after pulling on a bathrobe he stumbled from the house and toward the only safety he could think of. Arthur could solve anything and he always took care of his Little Bird. The one thing Merlin could count on in his life was that he belonged to Arthur.


End file.
